1. Field of the Invention
The present invention relates to a dye-containing curable composition suitable for forming a colored image, which constitutes a color filter used in liquid crystal display devices or solid image pickup devices, as well as a color filter using the dye-containing curable composition, and a method of manufacturing the same.
2. Description of the Related Art
As a method of manfacturing color filters using a photoresist, the following methods have long been known: staining technique comprising pattern formation with a photoresist, followed by pattern staining; electrodeposition comprising formation of a pre-patterned transparent electrode and subsequent pattern formation by ionization of a resin containing pigment dissolved/dispersed in a solvent by voltage application; printing method by offset printing with ink containing thermosetting resin or ultraviolet-curing resin; and pigment dispersing method using a color-resist agent in which a coloring agent such as pigment is dispersed in a photoresist material. Recently major method is the pigment-dispersing method.
Specifically, a colored radiosensitive composition is applied on a substrate by a spin coater or roller coater, and dried to form a film, on which pattern exposure is made and developed to generate colored pixels. This operation is repeated plural times according to the number of hue to give a color filter. For example, these processes are described in JP-A Nos. 1-102469, 1-152499, 2-181704, 2-199403, 4-76062, 5-273411, 6-184482, and 7-140654.
In recent years, the application of color filters has been expanded from liquid crystal display devices (LCD) to solid image pickup devices such as CCDs. In other words, in the solid image pickup devices, there have been strong demands for higher precision, and the pixels tend to be miniaturized in accordance with a higher density in picked up images. From this point of view, an organic pigment for use as a colorant inevitably needs to have finer particles. There is a limitation, however, in the primary particle size of the organic pigment, resulting in color irregularities caused by bulky particles. In order to solve such a problem, for example, JP-A No. 6-75375 has proposed a dye-type curable composition by incorporating a dye as a coloring agent in the medium of the curable composition in a dissolved state, and examined its practical use.
However, the curable composition containing a dye gives rise to other problems described below:
(1) Since a conventional pigments are low in solubility in either an alkaline aqueous solution or an organic solvent, it is difficult to obtain a liquid curable composition having a desired spectrum;
(2) Since most of dyes interact with another component contained in the curable composition, it is difficult to adjust the solubility of the cured portion and non-cured portion (developing property);
(3) When the molar extinction coefficient (ε) of the dye is small, a large amount of the dye needs to be added so that other components, such as a polymerizable compound (monomer), a binder and a photo-polymerization initiator, in the curable composition have to be reduced, causing problems such as poor curing property in the composition, degradation in heat resistance after curing and degradation in the developing property in (non)cured portions; and
(4) Dyes are in general inferior to pigments in light resistance and heat resistance.
Moreover, when used in production of a color filter for use in a solid image pickup device, the film thickness of the composition has to be in 1.5 μm or thinner. Therefore, it is necessary to add a large amount of pigment into a curable composition, resulting in the above-mentioned problems.
As described above, it has been difficult to achieve appropriate performances required for practical use as a high-precision color filter for a solid image pickup device, that is, miniaturized colored patterns and thin-films.
On the other hand, for example, JP-A No. 59-30509 has disclosed a color solid image pickup device which employs an acidic dye that has a pyridinium cation, a quinorium cation and a quaternary ammonium ion containing only one nitrogen atom as a counter cation. When the counter cation of the acidic dye is a cation containing a nitrogen atom, only one nitrogen ion is contained in one counter cation. Further it is not an aliphatic cyclic amine compound having no unsaturated bond when the aliphatic cyclic amine compound contains only one nitrogen atom. There is a problem that the resulting pattern (pixels) is insufficient in its solvent resistance, and further improvements have been demanded.